Re: Simplify for ca^2+sa^2==1
- To: mathgroup at smc.vnet.net
- Subject: [mg26370] Re: [mg26339] Simplify for ca^2+sa^2==1
- From: BobHanlon at aol.com
- Date: Wed, 13 Dec 2000 02:41:28 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
If you are using version 4: ((1 + ca^2 + sa^2)(b + 3 + 5ca^2 + 5sa^2))/((4 - ca^2 - sa^2)(x - 3y + ca^2 + sa^2)); Simplify[%, (ca^2 + sa^2) == 1] (2*(8 + b))/(3*(1 + x - 3*y)) Bob Hanlon In a message dated 12/12/00 3:35:54 AM, hanssen at Zeiss.de writes: >in a lengthy expression, I know, a lot >of simplification can be done, if Simplify >and the like would take into account that >for varaibles ca and sa > >ca^2+sa^2==1 > >I know, that I can set ca=Sqrt[1-sa^2] and >deal with the branch cut by hand. > >The bad thing is, that these ca^2 and sa^2 >are expanded out in lenghty subexpressions >involving lots of other symbols. So far, I >have found no way (but would be glad, if >someone could advise me one), to factor out >(ca^2+sa^2). > >Unfortunately, there are also terms, where >(1+ca^2+sa^2) or (2*ca^2+2*sa^2) can be >factored out, also others with (-ca^2-sa^2) >and so on. > >Any general tip, how to best cope with such >algebraic manipulations? >